M. K. Debe, “Novel catalysts, catalyst support and catalyst coated membrane methods,” in Handbook of Fuel Cells, Fundamentals Technology and Applications, Vol. 3, eds. W. Vielstich, A. Lamm and H. Gasteiger, John Wiley and Sons, p. 576 et seq., describes nanostructured thin film catalysts which may be useful as fuel cell catalysts.
U.S. Pat. No. 5,879,827, the disclosure of which is incorporated herein by reference, discloses nanostructured elements comprising acicular microstructured support whiskers bearing acicular nanoscopic catalyst particles. The catalyst particles may comprise alternating layers of different catalyst materials which may differ in composition, in degree of alloying or in degree of crystallinity.
U.S. Pat. App. Pub. No. 2002/0004453 A1, the disclosure of which is incorporated herein by reference, discloses fuel cell electrode catalysts comprising alternating platinum-containing layers and layers containing suboxides of a second metal that display an early onset of CO oxidation.
U.S. Pats. Nos. 5,338,430, 5,879,828, 6,040,077 and 6,319,293, the disclosures of which are incorporated herein by reference, also concern nanostructured thin film catalysts.
U.S. Pats. Nos. 4,812,352, 5,039,561, 5,176,786, and 5,336,558, the disclosures of which are incorporated herein by reference, concern microstructures.
U.S. patent application Ser. No. 10/674,594, the disclosure of which is incorporated herein by reference, discloses fuel cell cathode catalysts comprising nanostructures formed by depositing alternating layers of platinum and a second layer onto a microstructure support, which may form a ternary catalyst.
U.S. Pat. No. 5,079,107 discloses a catalyst for a phosphoric acid electrolyte fuel cell comprising a ternary alloy of Pt—Ni—Co, Pt—Cr—C or Pt—Cr—Ce.
U.S. Pat. No. 4,985,386 discloses a catalyst on a carbon support, the catalyst comprising carbides of Pt, carbides of a second metal selected from Ni, Co, Cr and Fe, and optionally carbides of Mn. The reference also discloses a method of making a carbon supported catalyst by reductive deposition of metal ions onto carbon supports followed by alloying and at least partial carburizing of the metals by application of heat and carbon-containing gasses.
U.S. Pat. No. 5,593,934 discloses a catalyst on a carbon support, the catalyst comprising 40-90 atomic % Pt, 30-5 atomic % Mn and 30-5 atomic % Fe. The reference includes comparative examples purportedly demonstrating carbon-supported catalysts comprising 50 atomic % Pt, 25 atomic % Ni and 25 atomic % Co; 50 atomic % Pt and 50 atomic % Mn; and Pt alone.
U.S. Pat. No. 5,872,074 discloses a catalyst made by first preparing a metastable composite or alloy which comprises crystallites having a grain size of 100 nm or lower and then leaching away one of the elements of that alloy.
Markovic et al., Oxygen Reduction Reaction on Pt and Pt Bimetallic Surfaces: A Selective Review, Fuel Cells, 2001, Vol. 1, No. 2 (pp. 105-116) examines reactions at crystal surfaces of bimetallic Pt—Ni and Pt—Co catalysts made by underpotential deposition method, the classical metallurgical method and deposition of pseudomorphic metal films.
Paulus et al., Oxygen Reduction on Carbon-Supported Pt—Ni and Pt—Co Alloy Catalysts, J. Phys. Chem. B, 2002, No. 106 (pp. 4181-4191) examines commercially available carbon-supported catalysts comprising Pt—Ni and Pt—Co alloys.
U.S. patent application Ser. No. 11/248,441, filed Oct. 12, 2005, discloses certain nanostructured thin film catalysts including three or more metallic elements which may be useful as fuel cell catalysts.
M. Lefevre, J. P. Dodelet, J. Phys. Chem. B, 104 (2000) 11238 and F. Jaouen, S. Marcotte, J. P. Dodelet, G. Lindbergh, J. Phys. Chem. B, 107 (2003) 1376 purportedly describe a Fe—N2—Cx active center for catalytic activity and postulate that, for high activity, all three elements must be present and high nitrogen concentration must be achieved on the surface of the carbon support, where nitrogen would preferably be in pyridinic form.